Autism is a severe, lifelong developmental disorder that affects approximately 1.6/1000 individuals. What goes awry in brain development in autism is not known. As a result, there is no treatment targeting the pathologic process underlying autism and no way to prevent the disorder. The goal of this component is to define morphometric and functional brain abnormalities that are specific to autism and to describe how the abnormalities are related to each other and to clinical features of autism. To accomplish this goal, we will collect cross-sectional and longitudinal morphometric magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), functional magnetic resonance imaging (fMRI), and magnetic resonance spectroscopy (MRS) data on 73 children and adults with autism and 54 controls, with a special focus on the temporal lobe. We will describe longitudinal changes in total and regional brain volumes in autism, including gray and white and regional temporal lobe volumes. Within individuals and study groups, we will describe how abnormalities in volume and size relationships of temporal lobe structures are related to 1) abnormalities in the integrity and anatomy of white matter tracts on DT1, 2) abnormalities of brain activation on fMRI, and 3) chemical abnormalities on MRS. In addition, we will compare the variation in morphometric and functional brain phenotypes in related individuals with autism in large Utah kindred being studied in the Genetics component.